The only thing I don't know how to do is cut the holes to install these ventilation panels and this pet door I found cheap. I also need to figure out how to attach 2 roosts inside since I don't know whether the shed walls are strong enough to support the weight of my chickens (flock of 10 birds, 7 of them under 4 pounds, one fatty at 6lbs and 2 standard brahmas that never roost, the lazy butts), but I'll figure something out.

so any ideas on how I can cut holes in it without breaking the panels? XD

You should be able to drill a starter hole then cut with a reciprocating saw. I'd put the roost on its own supports, myself, kind of like a table with roosts instead of a table top. This is how mine works. The treated uprights are buried maybe 6" or 8", just enough to prevent much wobble.